It has been the practice in, for example, aluminum electro-smelting operations to utilize aluminum bus bars which have affixed thereto copper contacts to which copper anode or furnace electrode hangers are clamped. The contact may take the form of a square or diamond-shape plate which is simply Mig welded along two or all four edges of the contact plate to the vertical major face of the aluminum bus.
This attachment system has a number of drawbacks. The first is that the connection does not provide a very good electrical connection between the bus and contact plate. The welding may cause a slight distortion of the plate, and, in any event, the current flows almost completely through the edge welds and not through the major flat surfaces even though they are supposedly abutting. This problem is made worse by wear and tear in the bus itself. Aluminum is a relatively soft metal and over years of use is subject to denting and scratching. The exposed face of the bus can become rather beat up. Without clamping pressure over the entire major surface and good area-to-area contact, the abutting surfaces with any irregularities or distortions create a small air gap, so that the major area of the plate facing the face of the bar acts like the plate of a capacitor. The connection has much higher resistance than it should.
Another major problem is that Mig welding requires the power to the system to be shut down. This can be costly and disturbing to the entire process. Power to electrometallurgical or smelting systems is designed to be continuous and literally run for months or even years. Power shutdowns can be very costly. Even where the power shutdowns are scheduled in advance, the extent of the shutdown for maintenance, repairs or replacements is, wherever possible, minimized. For many large scale electrical consumers, such as an electrical smelting operation, power is paid for, whether used or not. Also with scheduled power shutdowns and maintenance windows, it is then inherent that repairs or replacements may not be made when they should be made, making the system in that way inefficient.
Accordingly, the Mig welding connection process provides neither a good electrical nor necessarily a good mechanical connection between the two dissimilar metals.
It would be desirable to provide a connection between the two dissimilar metals which would be both a good electrical connection and a good long-lasting mechanical connection. It would also be desirable if the connection could be made without shutting off the power.